The systemic administration of drug agents, such as by transoral or intravenous means, treats the body as a whole even though the disease to be treated may be localized. In such a case, systemic administration may not be desirable because, for example, the drug agents may have unwanted effects on parts of the body which are not to be treated, or because treatment of the diseased part of the body requires a high concentration of drug agent that may not be achievable by systemic administration.
It is therefore often desirable to administer drug agents at a localized site within the body. Common examples include cases of localized disease or occluded body lumens. Various methods have been proposed for such localized drug administration. For example, U.S. Pat. No. 5,304,121, hereby incorporated by reference, discloses a method of delivering water-soluble drugs to tissue at desired locations of a body lumen wall. The method generally includes the steps of impregnating a hydrogel polymer on an expandable catheter with an aqueous drug solution, inserting the catheter into a blood vessel to a desired location, and expanding the catheter against the surrounding tissue allowing the release of the drug to the tissue. This method of localized drug delivery using hydrogel polymer impregnation has a limitation of being applicable to drug agents which are dissolved in water at concentrations sufficient for therapeutic gel loading levels. There thus exists a need for a method and apparatus for the localized delivery of drug agents within the body, where the drug agents are substantially water-insoluble. Moreover, there exists a need for a method and implantable device that provides a sustained release of such substantially water-insoluble drug agents over a time frame effective to inhibit proliferative disease.